Primary Site Failure and Backup Site Activation
Activation of the Disaster Recovery site begins with
verification of directory services and DNS resolution. Because the DR site
should already contain a directory server that is also hosting Active Directory-integrated
DNS, these services should be healthy, current, and largely unaffected by the
outage of the production site.
There are three basic steps that you complete to
perform a data centre switchover, after making the initial decision to activate
the second data centre:
- Terminate a
partially running data centre: This
step involves terminating Mailbox Service in the primary data centre, if any
services are still running. This is particularly important for the Mailbox
server role because it uses an active/passive high availability model. If
services in a partially failed data centre aren’t stopped, it’s possible for
problems from the partially failed data centre to negatively affect the
services during a switchover back to the primary data centre. - Activate the
Mailbox servers: This step
begins the process of activating the second data centre. This step can be
performed in parallel with step 4 because the Microsoft Exchange services can
handle database outages and recover. Activating the Mailbox servers involves a
process of marking the failed servers from the primary data centre as
unavailable followed by activation of the servers in the second data centre.
The activation process for Mailbox servers depends on whether the DAG is in
database activation coordination (DAC) mode. For more information about
database activation coordination mode, see Understanding Datacenter Activation
Coordination Mode - Activate the other
server roles This involves
using the URL mapping information and the Domain Name System (DNS) change
methodology to perform all required DNS updates. The mapping information
describes what DNS changes to perform. The amount of time required to complete
the update depends on the methodology used and the Time to Live settings on the
DNS record (and whether the deployment’s infrastructure honours the TTL)
These steps are described in more detail in the following
Terminate a partially running datacenter
If any DAG members in the failed datacenter are still
running, they should be terminated. When the DAG is in DAC mode, the specific
actions to terminate any surviving DAG members in the primary datacenter are as
follows:
- If the production mailbox servers are online and accessible, run the
following commands in the production datacentre:
Stop-DatabaseAvailabilityGroup
–Identity DAG –MailboxServer MBX SERVER NAME 1
Stop-DatabaseAvailabilityGroup
–Identity DAG –MailboxServer MBX SERVER NAME 2
- If the production mailbox servers are offline, run the following
commands in the production datacentre:
Stop-DatabaseAvailabilityGroup
–Identity DAG –MailboxServer MBX SERVER NAME 1 -ConfigurationOnly
Stop-DatabaseAvailabilityGroup
–Identity DAG –MailboxServer MBX SERVER NAME 2 -ConfigurationOnly
- In the DR site run the following command:
Stop-DatabaseAvailabilityGroup
–Identity DAG – ActiveDirectorySite SITE-A -ConfigurationOnly
1.1.2
Activating Mailbox Servers
When the DAG is in DAC mode, the steps to complete
activation of the mailbox servers in the second datacenter are as follows:
- Stop the Cluster Service on the DAG member in the DR Site (MBX SERVER
NAME).- a.
Net stop Clussvc or use
the Services snap-in - Restore the DAG in the DR site as follows:
- a.
Restore-DatabaseAvailabilityGroup
–Identity DAG –ActiveDirectorySite EXCH-DR
Set-MailboxServer
–Identity MBX SERVER NAME –DatabaseCopyAutoActivationPolicy Unrestricted
- Bring databases
- online:
Get-MailboxDatabase
| Move-ActiveMailboxDatabase -ActivateOnServer MBX SERVER NAME
Verify that all databases are mounted.
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